Multiple electrode vectors for implantable cardiac treatment devices

• US 20050192507A1
• Filed: 05/02/2005
• Published: 09/01/2005
• Est. Priority Date: 11/21/2001
• Status: Active Grant

• Current Assignee: Cameron Incorporated (Schlumberger NV)
• Original Assignee: Cameron Incorporated (Schlumberger NV)
• Inventors: Bardy, Gust H., Warren, Jay A.
• Granted Patent: US 7,627,367 B2
• Time in Patent Office: Days
• US Class Current: 600/512
• CPC Class Codes: A61B 5/076 Permanent implantations telemetry using implanted circuitry A61B5/0031; implanted stimulators for therapy A61N1/3605, A61N1/362, A61N1/372
• CPC Class Codes: A61B 5/276 Protection against electrode failure
• CPC Class Codes: A61B 5/283 Invasive
• CPC Class Codes: A61B 5/304 Switching circuits
• CPC Class Codes: A61B 5/318 Heart-related electrical modalities, e.g. electrocardiography [ECG]
• CPC Class Codes: A61B 5/7207 of noise induced by motion artifacts
• CPC Class Codes: A61N 1/3622 comprising two or more electrodes co-operating with different heart regions
• CPC Class Codes: A61N 1/3925 Monitoring; Protecting

Abstract

The implantable cardiac treatment system of the present invention is capable of choosing the most appropriate electrode vector to sense within a particular patient. In certain embodiments, the implantable cardiac treatment system determines the most appropriate electrode vector for continuous sensing based on which electrode vector results in the greatest signal amplitude, or some other useful metric such as signal-to-noise ratio (SNR). The electrode vector possessing the highest quality as measured using the metric is then set as the default electrode vector for sensing. Additionally, in certain embodiments of the present invention, a next alternative electrode vector is selected based on being generally orthogonal to the default electrode vector. In yet other embodiments of the present invention, the next alternative electrode vector is selected based on possessing the next highest quality metric after the default electrode vector. In some embodiments, if analysis of the default vector is ambiguous, the next alternative electrode vector is analyzed to reduce ambiguity.

Claims

1. A method of cardiac signal analysis comprising:

capturing a cardiac event along first and second sensing vectors using electrodes implanted in a patient to yield first and second event representations;

analyzing the cardiac event by use of the first event representation to reach a first result;

observing whether the first result is determinative and, if not,

analyzing the cardiac event by use of the second event representation.

2. The method of claim 1, wherein the step of determining whether the first result is determinative is performed in a manner wherein, if the first result unambiguously indicates a non-malignant cardiac rhythm, the first result is found to be determinative.

3. The method of claim 1, wherein the step of analyzing the cardiac event by use of the first event representation includes observing a correlation between the first event representation and an event template, wherein the first result is related to the correlation.

4. The method of claim 3, wherein the first result is a score from correlation waveform analysis performed between the first event representation and the cardiac template.

5. The method of claim 3, wherein the first result is related to a variability in a set of correlation waveform analysis scores, the set of correlation waveform analysis scores including a correlation waveform analysis score for the first event representation and the event template, and a number correlation waveform analysis scores for first event representations for previous cardiac events and corresponding event templates.

6. The method of claim 1, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed in a position for far-field sensing of the cardiac event; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed in a position for far-field sensing of the cardiac event.

7. The method of claim 1, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed subcutaneously inside the patient; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed subcutaneously inside the patient.

8. The method of claim 1, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed outside the patient'"'"'s thoracic cavity; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed outside the patient'"'"'s thoracic cavity.

9. A method of cardiac signal analysis comprising performing the following steps for a number of cardiac events:

capturing an individual cardiac event along first and second sensing vectors using electrodes implanted in a patient to yield first and second event representations;

analyzing the first and second event representations to generate a first metric corresponding to the first event representation and a second metric corresponding to the second event representation;

comparing the first metric to the second metric; and

selecting one of the first or second event representations as a primary event representation, and identifying the non-selected event representation as an alternate event representation for the individual cardiac event.

10. The method of claim 9, further comprising:

analyzing the primary event representation to generate a first result;

observing whether the first result is determinative and, if not,

analyzing the cardiac event by use of the alternate event representation.

11. The method of claim 10, wherein the step of determining whether the first result is determinative is performed in a manner wherein, if the first result unambiguously indicates a non-malignant cardiac rhythm, the first result is found to be determinative.

12. The method of claim 10, wherein the step of analyzing the primary event representation includes observing a correlation between the primary event representation and an event template, wherein the first result is related to the correlation.

13. The method of claim 12, wherein the first result is a score from correlation waveform analysis performed between the primary event representation and the cardiac template.

14. The method of claim 9, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed in a position for far-field sensing of the cardiac event; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed in a position for far-field sensing of the cardiac event.

15. The method of claim 9, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed subcutaneously inside the patient; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed subcutaneously inside the patient.

16. The method of claim 9, wherein the step of capturing the cardiac event includes:

observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed outside the patient'"'"'s thoracic cavity; and

observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed outside the patient'"'"'s thoracic cavity.

17. A method of cardiac signal analysis comprising:

A) capturing a cardiac event along first and second sensing vectors from sensors implanted in a patient to yield first and second event representations;

B) analyzing the cardiac event by use of the first event representation to reach a first result;

C) observing whether the first result is determinative and, if not, analyzing the cardiac event by use of the second event representation;

wherein;

the step of determining whether the first result is determinative is performed in a manner wherein, if the first result unambiguously indicates a non-malignant cardiac rhythm, the first result is found to be determinative;

the step of analyzing the cardiac event by use of the first event representation includes observing a correlation between the first event representation and an event template, wherein the first result is related to the correlation; and

the step of capturing the cardiac event includes observing the cardiac event with a first electrode set defining the first sensing vector, the first electrode set being disposed in a position for far-field sensing of the cardiac event, and observing the cardiac event with a second electrode set defining the second sensing vector, the second electrode set being disposed in a position for far-field sensing of the cardiac event.

18. The method of claim 17, wherein steps A, B, and C are performed for a plurality of cardiac events to determine whether the patient is experiencing a malignant cardiac condition.

19. The method of claim 17, wherein each electrode making up part of the first electrode set and the second electrode set is disposed subcutaneously in the patient.

20. The method of claim 17, wherein each electrode making up part of the first electrode set and the second electrode set is disposed at a nonvascular location exclusive of the patients heart.